21518064 has 120 divisors (see below), whose sum is σ = 64415520. Its totient is φ = 6690816.

The previous prime is 21518059. The next prime is 21518083. The reversal of 21518064 is 46081512.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 241732 + ... + 241820.

It is an arithmetic number, because the mean of its divisors is an integer number (536796).

Almost surely, 2^21518064 is an apocalyptic number.

21518064 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21518064, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32207760).

21518064 is an abundant number, since it is smaller than the sum of its proper divisors (42897456).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21518064 is a wasteful number, since it uses less digits than its factorization.

21518064 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 199 (or 190 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 27.

The square root of 21518064 is about 4638.7567299870. The cubic root of 21518064 is about 278.1427419394.

Adding to 21518064 its reverse (46081512), we get a palindrome (67599576).

The spelling of 21518064 in words is "twenty-one million, five hundred eighteen thousand, sixty-four".